Offshore risers pipeline repair

This chapter will first outline the conventional offshore riser repair techniques and their limitations which, in turn, provide the motivation for adoption of composite repair. A brief discussion about the application of FRPC in pipeline repair, its limitations, current practices, and material types will be given. A subsequent section provides information on the industrial design and safety standards used in designing and assessing the performance of offshore risers, corroded pipelines, and pipelines repaired with FRPC. The typical loading conditions of an offshore riser are also discussed so that the requirements of CRS can be understood. 

ASME B31.4 (2006) Pipeline Transportation for Hydrocarbon Liquid and Other Liquids and ASME B31.8 (2003) Gas Transmission and Distribution Piping System are standards related to the design of pipelines which provide information on the stress and strain limits of industrial oil and gas pipelines. Although not specihcally intended for offshore risers, these standards provide a good foundation for pipeline design that in turn defines the requirements on the repair using FRPC materials. 

Stress Engineering, Inc. is one of the major companies that has run multiple full-scale tests to validate the performance of numerous onshore pipeline composite repair products that are available in the market. Full reports documenting the vahdation of composite repair products are available (Alexander, 2005 Worth, 2005 Francini and Kiefner, 2006). Various publications on the development of the CRS for offshore riser application are also available under Chris Alexander of Stress Engineering, Inc. A program cosponsored by the Pipeline Research Council International, Inc. (PRCI) involves the full-scale testing of corroded risers with a CRS placed in a seawater test facility for 10,000 h subjected to combined pressure, tension and bending loads (Alexander, 2012). 

Alexander, C., Ochoa, O.O., 2010. Extending onshore pipeline repair to offshore steel risers with carbon-fiber reinforced composites. Composite Structures 92, 499—507. 

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